In the manufacture of portable electric drills, the chuck key is a seemingly minor element of the system which has been a continuing source of irritation to both the manufacturer and the user. The chuck key is necessary for adequate tightening of the chuck jaws on the shafts of various working implements. However, if the key design is selected so as to permit low cost manufacture, the design is inconvenient for the user. On the other hand, if the design chosen is reasonably convenient for the user, then the manufactured cost is unreasonably high.
A further problem with chuck keys lies in the fact that they must be a separate and freely movable element of the system and cannot be affixed to the drill. Consequently, they are easily lost which can cause substantial inconvenience.
A variety of chuck key constructions have been designed in the past which have solved one or another of these problems. For example, British Pat. No. 560,546, dated Apr. 7, 1944, discloses two versions of a chuck key in which generally wingshaped extensions of the key body are formed integrally therewith to provide a large flat gripping surface which is well suited for use by the operator. However, a chuck key of this design is relatively expensive to manufacture.
Another version of a chuck key is shown in British Pat. No. 1,396,859, dated June 11, 1975. In this design, a generally straight shaft is formed by bending operations to provide an approximation of a T-shape which is relatively inexpensive to manufacture. However, this design is less convenient and less comfortable for the operator to use, particularly if significant force is to be applied to ensure adequate tightening.
Another chuck key design which is still less expensive to manufacture is the widely known and used L-shaped key. This design is basically similar to that of the British Pat. No. 1,396,859 except that the handle portion is bent only once to form an L.
An improved chuck key of simple construction is shown in the recent U. K. Registered Design No. 974,037, issued Oct. 27, 1976. This design is basically similar to the handle illustrated in U.S. Pat. No. 3,213,720, dated Oct. 26, 1965 and also to a variety of similar handles used on such items as Allen wrenches and can opener keys.
Despite the variety of chuck key constructions available in the prior art, a continuing difficulty has been that of ensuring against the loss of the chuck key. The most satisfactory solution to this difficulty for the ultimate user is to tape the key to the cord set of the drill. However, this is not a good solution for the manufacturer and therefore it is not of assistance in preventing loss and theft of keys from the cartons during shipping and distribution.
A further difficulty sometimes encountered is that caused by a careless operator who turns the drill on while the key is in place in the chuck. The key can be thrown out with sufficient force to cause injury or damage.